The field of the present invention relates to portable containers for transporting devices sensitive to electrostatic discharge. More particularly, the field of the present invention includes containers which, while closed, protectively shield their contents from potentially harmful external electrical and electromagnetic forces.
Printed circuit boards are typically stored and carried in either conventional packaging, antistatic bags, or electrically conductive containers. To store a plurality of such boards, a carrying device is often used.
These carriers are often ribbed to provide slots for the insertion of each circuit board to be stored. Both injection molding and blow molding technology have been employed in producing such carrying means.
Containers have been developed, especially containers for portable use, as for example in the device replacement market, which protect electrically sensitive devices from damage. One type is a small box-like container that has conductive, sponge or foam sheets into which the device terminals are temporarily embedded. An example is found in U.S. Pat. No. 4,333,565.
A portable work station is described in U.S. Pat. No. 4,494,651 in which electrically conductive material such as carbon black particles, is blended with thermoplastic material to make an electrically conductive case.
With reference to carrying devices for storing a plurality of printed circuit boards or similar parts, British Pat. No. GB2023102B describes a device including a plastic container with an insert made of plastic and comprising a rectangular frame with a series of parallel grooves and optionally dividers for storing printed circuit boards or similar parts.
A useful feature of such a device would be the capacity to safely and securely store a multiplicity of printed circuit boards and other electrostatic discharge (ESD) sensitive devices, while also providing a completely enclosed container which will protect such electrically sensitive devices from electrical and electromagnetic influence and mechanical abuse during distribution and storage of the contents.
A further advantage would be the use of relatively inexpensive blow molding technology to produce such a container. Unfortunately, close tolerances in compactly storing printed circuit boards and similar devices of relatively small dimensions are often difficult to achieve in a blow molding technology. While injection molding processes would meet these critical tolerances, such processes are considerably more expensive and complex.
It is therefore an object of the present invention to provide a relatively inexpensive container for carrying a plurality of printed circuit boards and other ESD sensitive devices.
It is also an object of the present invention to provide such a container which nevertheless meets the close tolerances required in storing such devices.
It is still another object of the present invention to provide such a container in which ESD sensitive devices such as printed circuit boards may be stored in a very compact arrangement so as to utilize a minimal volume of space.
It is yet another object of the present invention to provide a container for ESD sensitive devices in which the individual devices are protected to some extent from dimensional changes in the overall container created by external stress on the container.